Object of type System.Int32 cannot be converted to type System.Web.Security.Cryptography.Purpose

Well John West has the solution. This blog post explains how you can resolve the Object of type 'System.Int32' cannot be converted to type 'System.Web.Security.Cryptography.Purpose' error that you may receive when you try to access a user interface in the Sitecore ASP.NET web Content Management System (CMS) after installing Visual Studio 2012 or .NET 4.5.